Solubility and phase separation of benzocaine and salicylic acid in 1,4-dioxane-water mixtures at several temperatures.

The solubilities of benzocaine and salicylic acid were determined in water-dioxane mixtures at several temperatures (5-40 degrees C for benzocaine and 10-40 degrees C for salicylic acid). The solubility curves as a function of dioxane ratio showed a maximum at 90% dioxane at all temperatures. Above 25 degrees C, the homogeneous mixture splits into two liquid immiscible phases.